450 Astronomical Society. 
ASTRONOMICAL SOCIETY OF LONDON. 
Dec. 14. A Letter was read from Captain Basil Hall, dated 
Valparaiso, May 19, 1821, giving an account of a comet which 
had recently appeared in that quarter; and communicating a 
number of observations of the same: whence its orbit may be 
deduced when they are published. At the conclusion of his let- 
ter, Captain Hall mentions a fact which either is not generally 
known, or dees not appear to have been sufficiently attended to: 
which is, that occultations of the stars by the moon are eusily 
discernible at sea; and that he himself has made several obser- 
vations of this kind, and regrets that they are not announced in 
any ephemeris. As this mode of determining the longitude is 
much preferable to that by the eclipses of Jupiter’s satellites, 
there will be no occasion for marine chairs, or any other con- 
trivance for observing them. 
A Letter was communicated, by the American Minister, from 
Mr. Lambert, of Washington, containing some tables for deter- 
mining the moon’s semidiameter in time, or the interval of pas- 
sage from either limb to the centre, when passing the meridian. 
The author conceives this mode of determining the longitude to 
possess many advantages. 
A Letter was also received from the Rev. M. Ward, relative 
to an opinion he had formed, that the western cavities of the 
moon would reflect sufficient light to produce a phosphoric ap- 
pearance, similar to what he had before observed in May last. 
He was confirmed in his opinion by an observation of the spot 
Manilius, for the space of five minutes, on November 20th ; 
and by a faint appearance, precisely in the situation of Menelaus. 
Mr. Ward conceives that each spot has not only a particular 
month, but also a particular day in each lunatiou, on which it 
is most favourably situated for such observations. 
The next meeting of the Society will be on January 11, 1822. 
XCII. Intelligence and Miscellaneous Articles. 
TO OUR KEADERS. 
Wirn the present Number is given a portrait of the Eprror. 
It is but proper that he should state that the plate was not en- 
graved at his own expense. Mr. Henry Fisher, the spirited 
proprietor of the Caxton Press, some time ago requested to have 
the loan of a portrait, painted by Mr. Frazer, for the purpose of 
having it engraved for the Imperial Magazine; and in return for 
what 
